Biodiversity, in the simplest possible terms, is the range and variety of living things on the planet. The really interesting thing about biodiversity is the sheer number of species that haven't been discovered yet: the two million or so recorded so far are only a fraction of the estimated total species on earth, which may be as high as 100 million. In fact, new species are discovered all the time.
The more species we find—or lose to extinction—the more we realize how the dynamics of the natural world are a complex web of cause, effect, and interdependency. Evolution has given the planet mutually supportive ecosystems—webs of species that enable and encourage healthy populations in other species, and so in the environment, around them. We're losing species at an unprecedented rate, and that's bad news for life on Earth— including humanity. Here are some of the surprising factors that are affecting our planet's biodiversity.